Process for the dyeing of nylon fibers and fabrics with 5-chlorosalicylic acid



United States Patent O PROCESS. FoR THE. DYEING or. NYLON FIBERSFABRICS, WITH. S-CHLOROSALICYLIC ACID .3 Claims, (Cl. 8--55)Thiszinvention relates to the dyeing: of fibers, andmore specifically,to .a new andimproved methocl'for, dyeing fibers-ands fabrics of nylon,a synthetic linear polyamide.

Conventional methods employed in the dyeingof nylon fibers or fabricsinvolve the use .of various organic acids such as benzoic acid,salicyclic acid, tannic acid,,-etc.- as carriers or dye assistants. The.actual mechanism by which these acidsv improve the dyeingcharacteristicstof the'fibenor fabric is not known but it is believedthata swellingof the material is induced. which-allowsthe dye todisperse into the fiber where it is held until the carrier issremorved.at alater step in the dyeing= ;operation-. In the dyeing process,quantities as high as %,015 the organic acids are used as dyeassistants. The useof such highiconcentrationsof. swelling. agents isundesirable: in that. .a resulting. shrinkage orplasticization. .of.the. nylon fiber. is elfected- Various attempts to, reduce theconcentration offthe acid carrier invariably haveresulted in acorresponding reduction of the color yield, obtained in the subsequentdyeing step. In other words deeper coloration of the nylon. material tobe. dyed? could onlyfbe obtained, hitherto, by increasing theconcentration of the swelling agent used.

It-has now been found that substantially higl'rcolor yields are obtained'in the dyeing of'nylon fibers and fabrics-when the material is exposedto a pretreatment with: aqueous solutions containing relatively smallamounts, i. e. as low as about 0.5% by weight, of eitherS-chlorosalicylic acid or cresotinic acid (hydroxytoluic acid) prior tothedyeing operation. Surprisingly, the nylon fibers and fabricspretreated with eithervof these organic acids are dyed to a deeper shadeby various types of dyes as compared with untreated nylon fabric. orvnylon fiber treated with conventional carriers such: as; benzoic orsalicylic acid or tannic acid, .the latter acid being used in aconcentration as high as 10%. Because.

of their greater ability to increase the receptivity of nylontoivariousdyes, S-chlorosalicyclic acidorcresotinic acid may be used ina concentration. as:'low'as;0i5'% to obtain maximum. color depth asdistinguished. from the organic acids used hitherto which required aconcentration ranging from at least 2% to as high as 10% to achieveresults considered to-befarless satisfactory in nature.

In a more specific embodiment of this invention, nylon fabric sampleswere treated in a relaxed state for three minutes at the boil in bathscontaining from 015% to 3% by weight of either cresotinic acidorS-chlbrosalicylic acid in aqueous solutions thereof. The samples werethoroughly washed in warm water followed by cold water to remove theacid carrier and then dyed for about thirty minutes at a temperature of190 F. in a bath containing the appropriate dye.

Untreated samples of the same material were exposed in the same mannerto a dyeing treatment in order to provide a control or basis forcomparisons between samples exposed to pretreatment and those which hadnot. In a separate procedure, the fabrics were also treated with aqueoussolutions con- 2,743,231 Patented Apr. 24, 1956 taining from 0.5% to 3%salicylic acid by weight and the results obtained by, the-use-of thisacid were compared with those obtained by the use of the lowerconcentrations of 'S-chlorosalicylicacid or cresotinic acid. All of thenylon fabric samples subjectedtothese treat men-ts; were exposed tovarious dyes such' as acid dyes, direct dyes, and acetate dyes.Ir-ieachinstance, the samples pretreated with, 5-chlorosalicylicacid.and CI'ESG? tinicacidiwere considerably-.darkerin color thanieitherthesample's pretreated with-salicylic acid or the. samples that were notexposed to any pretreatment.

Additional advantages and features of this new and highly improvedprocess are set forth-in. the; following examples whichgdisclose. theprincipleof the.invention'.- and the preferred embodimentmof :applyingthat principle. It is understood, however, that these .examples'arermerely' illustrative andtnot :limitiativein nature; being capable: ofvariousrothermodifications;

EXAMPLE I Acid dyes Acid dyes are ordinarily employed in the dyeingofwo'olt These dyes-are azo dyes of lowermol'ecular weight. Nylon fabricsamples were treated in a relaxed state for: three minutes at the boilin baths containing from- 0.5 to 3% -by weight of salicylic acid;cresotinic acid I andrS-chiorosali'cylicacid: The:sampleswere-thoroughlywashed: inc-warm water followed by cold water and then' dyedtogether'with' an untreatedsampleof the samernaterialzfor :30: minutesat F. in a. dyebath. containing.

l.% ;acid. dye (onwweight of the fabric) 2%; H2SO4..( on weight of thefabric) 10%. NaCl (on ,weight'of tl1e fabric) Direct dyes Directdyes-are used ordinarily in' dyeing cotton material. They are watersoluble azo dyes containingsul phonic: acid groups.

Usingrthe' procedure described in Example I, samples ofi nyllonpretreated: with-aqueous solutions containing flfOl'IIiiOlS to 3%- byweightxofwS chlorosalicylic acid, cresotinic acid and salicyclicacidwere dyed along? with an'untreated'sample ima dyebath containing-1%. ofPontamineBluez 3R. (Colour Index No. 464) orPontamine..Brilliant.Violet. (Prototyp Number 35-)" (both of which aremanufactured by E. I. du Pont de Nemours and Co.) and 20% of sodiumchloride based on the weight of the fabric. The water to fabric ratiowas 25:1. In this case also, the samples pretreated with 1 The ColourIndex Numbers and Prototype Numbers mentioned here and throughout thespecification are a standard of identification for commerciallyimportant organic dyes listed in the Technical Manual and Year Book ofAmerican Assn. of Textile Chemists and Colorists, volume XXVI, 1950,page 150. Also referred to in Library Guide for Chemists, Soule, McGrawHill Publishing Company, 1938.

3 S-chlorosalicylic acid and cresotinic acid were dyed to a much deepershade than were the untreated sample and the samples treated withsalicylic acid.

EXAMPLE III Acetate dyes These dyes are water insoluble and are normallyemployed in the form of aqueous dispersions.

The procedure described in Example I was repeated using a dyebathcontaining:

1% acetate dye-on weight of fabric 10% triton Xlon weight of fabric(alkylarylpoly ethylene oxide) (JACS 69, 334, 1947-Rohm and Haas Co.)

The water to fabric ratio was 30:1.

Acetamine Violet 2R (du Pont de Nemours and Co.) and Eastone Rubine C(Tennessee Eastman Corporation) were the acetate dyes used.

The samples pretreated with S-chlorosalicylic acid or with cresotinicacid were noticeably darker than those which were not pretreated orwhich were pretreated with salicylic acid.

EXAMPLE IV Comparison of activity of the acid carriers The relativeactivity of the various acid carriers in different concentrations andtheir effectiveness in increasing the affinity of nylon for varioustypes of dyes is shown in the following table. The activity wasdetermined by dyeing tests similar to those described in the precedingexamples. Samples pretreated with cresotinic acid, S-chlorosalicylicacid and salicylic acid were dyed with Eastone Yellow GNS and SRA RedV11 (acetate dyesmanufactured by Tennessee Eastman Corp.), PontamineBlue BR and Pontamine Brown NCR Conc. 150% (Colour Index No. 596)(direct dyes), Pontacyl Light Red BL Conc. and Pontacyl Brilliant Blue AConc. (acid dyes manufactured by E. I. du Pont de Nemours and Co.), andPonsol Brilliant Green 46 and Ponsol Dark Blue BRD Bbl. Pdr. (ColourIndex No. 1099) (vat dyes). In the following table the lightest shadeproduced has 4 acid is raised beyond about 1% and up to about 10%, forpractical reasons, the acid is used in a concentration of about 1%.

While the color values of the dyed nylon samples pretreated with5-chlorosalicylic acid, cresotinic acid at 7 and F. are higher thanthose of the salicylic acid pretreated sample and the sample that wasnot pretreated, there is a marked increase in the color value of samplespretreated with 5-chlorosalicylic acid or cresotinic acid at atemperature between about F. and the boiling point of the bath.

Maximum color values are obtained when the pretreating solutionscontaining as little as 0.5% of S-chlorosalicylic acid or cresotinicacid are used and when the pretreatment process is carried out at atemperature varying between 180 F. to 200 F. for a period of threeminutes and preferably, at a temperature of about F.

It is apparent from the foregoing that the invention is capable ofvarious modifications and that, therefore, it is intended and desired toembrace within the scope of this invention such modifications andchanges that are necessary to adapt it to varying conditions and uses,as defined by the scope of the appended claims.

We claim:

1. In a process for coloring nylon fibers and fabrics, the improvementwhich comprises pretreating the nylon material in an aqueous solutioncontaining from 0.5% to 1.5% by weight of 5-chlorosalicylic acid andwhile the aqueous solution is at a temperature between 180 F. and theboiling point of the aqueous solution, washing the material thus treatedand subsequently dyeing said material.

2. In a process for coloring nylon fibers and fabrics, the improvementwhich comprises pretreating the nylon material in an aqueous solutioncontaining from 0.5% to 1.5% by Weight of S-chlorosalicylic acid, saidpretreatment being efiected at a temperature ranging between about180-200 F., washing the material thus treated and subsequently dyeingsaid material.

3. In a process for coloring nylon fibers and fabrics, the improvementwhich comprises pretreating the nylon material in an aqueous solutioncontaining from 0.5% to 1.5% by weight of S-chlorosalicylic acid, saidprebeen indicated by the number 1. treatment being effected at atemperature of about 5-Ch1orosalicy1lc Acid cresotinic Acid SalicylicAcid 0 0'.- trol 0.5% 1.0% 1.5% 2.0% 3.0% 0.5% 1.0% 1.5% 2.0% 3.0% 0.5%1.0% 1.5% 2.0% 3.0%

Direct Dyes 0 6 6 5 0 5 5 6 5 6 1 1 2 2 3 1 Acid Dyes 5 s 5 6 6 6 0 5 65 1 1 1 2 a 1 Acetate Dyes I5 5 6 5 6 5 6 5 5 6 1 1 2 2 2 1 Vat. Dyes o5 5 s 5 4 5 0 5 5 1 1 1 2 3 1 190 F., washing the material thus treatedand subsequently dyeing said material.

References Cited in the file of this patent FOREIGN PATENTS GreatBritain Dec. 8, 1948 OTHER REFERENCES American Dyestuff Reporter forFebruary 4, 1952, p. P78.

American Dyestuif Reporter for May 14, 1951, p. 312.

1. IN A PROCESS FOR COLORING NYLON FIBERS AND FABRICES, THE IMPROVEMENTWHICH COMPRISES PRETREATING THE NYLON MATERIAL IN AN AQUEOUS SOLUTIONCONTAINING FROM 0.5% TO 1.5% BY WEIGHT OF 5-CHLOROSALICYLIC ACID ANDWHILE THE AQUEOUS SOLUTION IS AT A TEMPERATURE BETWEEN 180* F. AND THEBOILING POINT OF THE AQUEOUS SOLUTION, WASHING THE MATERIAL THUS TREATEDAND SUBSEQUENTLY DYEING SAID MATERIAL.